akkoma/lib/pleroma/gun/connection_pool.ex
rinpatch 45be1fe00e ConnectionPool: fix gun open errors being returned without an error tuple
When gun shuts down due to the host being unreachable, the worker
process shuts down with the same shutdown reason since they are linked.
Gun doesn't have error tuples in it's shutdown reason though, so we need
to handle it in get_conn.

Closes 
2020-08-01 18:02:26 +03:00

82 lines
2.4 KiB
Elixir

defmodule Pleroma.Gun.ConnectionPool do
@registry __MODULE__
alias Pleroma.Gun.ConnectionPool.WorkerSupervisor
def children do
[
{Registry, keys: :unique, name: @registry},
Pleroma.Gun.ConnectionPool.WorkerSupervisor
]
end
@spec get_conn(URI.t(), keyword()) :: {:ok, pid()} | {:error, term()}
def get_conn(uri, opts) do
key = "#{uri.scheme}:#{uri.host}:#{uri.port}"
case Registry.lookup(@registry, key) do
# The key has already been registered, but connection is not up yet
[{worker_pid, nil}] ->
get_gun_pid_from_worker(worker_pid, true)
[{worker_pid, {gun_pid, _used_by, _crf, _last_reference}}] ->
GenServer.call(worker_pid, :add_client)
{:ok, gun_pid}
[] ->
# :gun.set_owner fails in :connected state for whatevever reason,
# so we open the connection in the process directly and send it's pid back
# We trust gun to handle timeouts by itself
case WorkerSupervisor.start_worker([key, uri, opts, self()]) do
{:ok, worker_pid} ->
get_gun_pid_from_worker(worker_pid, false)
{:error, {:already_started, worker_pid}} ->
get_gun_pid_from_worker(worker_pid, true)
err ->
err
end
end
end
defp get_gun_pid_from_worker(worker_pid, register) do
# GenServer.call will block the process for timeout length if
# the server crashes on startup (which will happen if gun fails to connect)
# so instead we use cast + monitor
ref = Process.monitor(worker_pid)
if register, do: GenServer.cast(worker_pid, {:add_client, self()})
receive do
{:conn_pid, pid} ->
Process.demonitor(ref)
{:ok, pid}
{:DOWN, ^ref, :process, ^worker_pid, reason} ->
case reason do
{:shutdown, {:error, _} = error} -> error
{:shutdown, error} -> {:error, error}
_ -> {:error, reason}
end
end
end
@spec release_conn(pid()) :: :ok
def release_conn(conn_pid) do
# :ets.fun2ms(fn {_, {worker_pid, {gun_pid, _, _, _}}} when gun_pid == conn_pid ->
# worker_pid end)
query_result =
Registry.select(@registry, [
{{:_, :"$1", {:"$2", :_, :_, :_}}, [{:==, :"$2", conn_pid}], [:"$1"]}
])
case query_result do
[worker_pid] ->
GenServer.call(worker_pid, :remove_client)
[] ->
:ok
end
end
end